import sequtils, strutils
proc diamond*(letter: char): string = 
  let size = ord(letter) - ord('A')
  var carvas = sequtils.repeat(spaces(size * 2 + 1) & '\n', size * 2 + 1)
  for y in -size..size:
    for x in -size..size:
      if abs(x - y) == size or abs(x + y) == size:
        carvas[y + size][x + size] = chr(size - abs(y) + ord('A'))
  carvas.join